A workshop is valuable in certain circumstances. When do those circumstances arise, and when might you choose to conduct a workshop over other methods of education or training? There are a number of situations in which a workshop would be the best choice:
The beginning of something new. If your organization is adopting a new method, or your community initiative is taking a new track, there are often new pieces of information or ways of functioning that people must learn. A workshop, or series of workshops, is a way to introduce these in a short time and get people ready for the change.
The initial training of staff or volunteers. Workshops are often a good way to train new staff members or volunteers in the philosophy, methods, and functioning of your organization, or in techniques they'll need to do their jobs.